...DISCUSSION... 00Z ECMWF/GEFS GUIDANCE ARE IN AGREEMENT WITH THE GENERAL PERSISTENCE OF AN AMPLIFIED PATTERN MUCH OF THE PERIOD...HIGHLIGHTED BY A SLOW GENERAL EASTWARD PROGRESSION OF AN UPPER TROUGH OVER THE ROCKIES/TOWARD THE PLAINS FROM MID-WEEK ONWARD /DAYS 4-7/.

INITIALLY FOR DAY 4/WEDNESDAY...AT LEAST SOME SEVERE THREAT MAY EXIST ACROSS PORTIONS OF THE MIDWEST/OH VALLEY IN ASSOCIATION WITH A SOUTHEAST MOVING SURFACE LOW/COLD FRONT AND PARENT LOW AMPLITUDE SHORTWAVE TROUGH. A FEW STRONG TSTMS MAY ALSO BE POSSIBLE FOR PORTIONS OF SOUTHERN CA AS AN UPPER TROUGH/ASSOCIATED FRONT MOVES INLAND ON DAY 4/WEDNESDAY.

THEREAFTER...SEVERE POTENTIAL SHOULD INCREASE ACROSS PORTIONS OF THE PLAINS AS THE UPPER TROUGH APPROACHES THE REGION...ALTHOUGH INITIALLY LIMITED MOISTURE RETURN AND UNCERTAIN SPECIFIC EVOLUTION OF THE UPPER TROUGH PRECLUDE ANY 30 PERCENT SEVERE AREAS AT THIS TIME. NONETHELESS...CURRENT THINKING IS THAT AT LEAST ISOLATED/POTENTIAL SLIGHT RISK-CALIBER SEVERE THREATS COULD EXIST DAY 5/THURSDAY ACROSS PORTIONS OF THE SOUTH-CENTRAL HIGH PLAINS/PERHAPS ROCKIES FRONT RANGE...AND INTO DAYS 6-7 FRIDAY/SATURDAY ACROSS THE SOUTH-CENTRAL PLAINS POTENTIALLY INCLUDING PORTIONS OF KS/OK/NORTHWEST TX AND POSSIBLY THE ADJACENT MO VALLEY.

From Reed Timmer's facebook: Reed Timmer: Meteorologist and Extreme Storm ChaserModels are coming into agreement on a potentially very active severe weather pattern April 26-28+ across central/southern Plains, beginning in eastern CO/WY on April 26, then possibly KS/OK area thereafter. I'll be doing a free giveaway of weather radios from http://Palcycle.com/ later this afternoon. Stay tuned..

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"Auntie Em, Uncle Henry, its a TWISTER its a TWISTER!"Follow me on Twitter: @melwheat62

...DISCUSSION... 00Z ECMWF/GEFS GUIDANCE REMAIN IN AMPLE GENERAL AGREEMENT WITH THE CONTINUANCE OF A RELATIVELY AMPLIFIED PATTERN MUCH OF THE PERIOD. DEEP CONVECTIVE POTENTIAL WILL GENERALLY BE TIED TO AN EASTWARD PROGRESSING UPPER TROUGH DAYS 4-6...WITH A SOUTHERN STREAM SHORTWAVE TROUGH EXPECTED TO EJECT NORTHEASTWARD FROM THE DESERT SOUTHWEST TO THE CENTRAL PLAINS/MIDWEST BY DAYS 5/6 FRIDAY/SATURDAY.

IT IS LIKELY THAT AT LEAST SOME SEVERE POTENTIAL SHOULD EXIST ACROSS PORTIONS OF THE PLAINS TO MO VALLEY/MIDWEST AS THE UPPER TROUGH APPROACHES THE REGION THE LAST HALF OF THE WEEK. HOWEVER...AN INITIAL MODEST QUALITY/DEGREE OF MOISTURE RETURN...AND EVENTUAL POSSIBLE WEAKENING PHASE OF THE UPPER TROUGH OVER THE CENTRAL CONUS BY THE WEEKEND...PRECLUDE ANY 30 PERCENT SEVERE AREAS AT THIS TIME.

NONETHELESS...CURRENT THINKING BASED ON LATEST GUIDANCE IS THAT AT LEAST ISOLATED/POSSIBLE SLIGHT RISK-CALIBER SEVERE THREATS COULD EXIST DAY 4/THURSDAY INTO DAYS 5/6 FRIDAY/SATURDAY. FOR DAY 4/THURSDAY...THIS COULD BE ACROSS PORTIONS OF THE SOUTH-CENTRAL HIGH PLAINS/PERHAPS ROCKIES FRONT RANGE...INCLUDING A CORRIDOR ENCOMPASSING THE TX/OK PANHANDLES INTO EASTERN CO/FAR WESTERN KS. SUBSEQUENT SEVERE POTENTIAL COULD THEN DEVELOP EASTWARD ACROSS THE CENTRAL PLAINS/LOWER MO VALLEY INTO DAY 5/FRIDAY...WITH THE DEGREE/LIKELIHOOD OF DEVELOPMENT ALONG THE DRYLINE MORE UNCERTAIN WITH SOUTHWARD EXTENT INTO OK/TX. BY DAY 6/SATURDAY...A SEVERE RISK MAY EXTEND INTO PORTIONS OF THE OH VALLEY/MIDDLE MS VALLEY AND PERHAPS ARKLATEX/MID-SOUTH IN VICINITY OF THE EAST-SOUTHEAST ADVANCING COLD FRONT...ALTHOUGH SPECIFIC PREDICTABILITY IS MUCH MORE UNCERTAIN BY THIS TIME FRAME.

Not too impressive IMO: Strong cap will be in place (should be broken by 3000 CAPE), jet stream barely latching onto the system to decrease tornadic shearing, and just the overall weak demeanor of the storm.However, the system is negatively tilted, as seen in the 500mb image below.

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CENTRAL HIGH PLAINS...

...CO/SOUTHEAST WY FRONT RANGE AND CENTRAL/SOUTHERN HIGH PLAINS... 00Z-BASED MODELS ARE IN RELATIVELY GOOD AGREEMENT WITH THE EXPECTED NORTHEASTWARD-ADVANCEMENT OF A SOUTHERN STREAM SHORTWAVE TROUGH FROM THE DESERT SOUTHWEST EARLY THURSDAY TO THE CENTRAL HIGH PLAINS BY THURSDAY EVENING. THIS WILL LEAD TO HIGH PLAINS SURFACE CYCLOGENESIS/MOISTENING...ALTHOUGH IT DOES SEEM LIKELY THAT ESPECIALLY 00Z NAM/GFS REMAIN A LITTLE TOO AGGRESSIVE WITH THE WEST-NORTHWESTWARD EXTENT OF NEAR/ABOVE 60S F SURFACE DEWPOINTS ACROSS THE CENTRAL PLAINS.

NONETHELESS...SUFFICIENT MOISTENING IN CONJUNCTION WITH UPPER JET EXIT REGION/AMPLE FORCING FOR ASCENT AND LOW-LEVEL UPSLOPE SHOULD YIELD AT LEAST ISOLATED STRONG/SEVERE TSTM DEVELOPMENT DURING THE AFTERNOON...INCLUDING SOME SUPERCELLS CAPABLE OF LARGE HAIL. THIS SEEMS MOST PROBABLE FROM THE NORTHEAST CO/SOUTHEAST WY FRONT RANGE VICINITY INTO THE CENTRAL HIGH PLAINS. ANTICIPATED STRENGTH OF THE ELEVATED MIXED LAYER ALOFT PROVIDES UNCERTAINTY REGARDING THE POTENTIAL FOR MORE ISOLATED DEVELOPMENT ACROSS THE SOUTHERN HIGH PLAINS AREAS TO THE SOUTH OF THE WNW-ESE ORIENTED FRONTAL ZONE ACROSS KS.

...OH/TN VALLEYS TO MID-ATLANTIC STATES/CAROLINAS... UNCERTAINTIES FROM THE DAY 2/WEDNESDAY PERIOD CARRYOVER INTO THURSDAY...ESPECIALLY REGARDING THE LIKELIHOOD/EXTENT OF EARLY DAY PRECIPITATION AND THE EFFECTIVE LOCATION OF THE EAST-SOUTHEASTWARD MOVING COLD FRONT ACROSS THE REGION. EVEN SO...GIVEN A WESTERLY MOIST/UNSTABLE FEED IN CONJUNCTION WITH MODERATELY STRONG/CYCLONIC WEST-NORTHWESTERLY FLOW ALOFT...SEVERAL CORRIDORS OF ISOLATED SEVERE WIND/HAIL MAY OCCUR ACROSS THE REGION ESPECIALLY THURSDAY AFTERNOON/EARLY EVENING.

...LOWER MO VALLEY/MIDDLE MS VALLEY THURSDAY NIGHT... CURRENT INDICATIONS ARE THAT TSTMS SHOULD EXPAND INTO THE REGION/DEVELOP ON THE EDGE OF THE CAP THURSDAY NIGHT AS A LOW LEVEL JET STRENGTHENS. GIVEN THIS SCENARIO...THE PROXIMITY OF STEEP LAPSE RATES/RESERVOIR OF ELEVATED INSTABILITY SUGGEST SEVERE HAIL WOULD BE POSSIBLE WITH THE STRONGEST STORMS.

...SOUTHEAST MT/FAR NORTHEAST WY... A FEW STRONG TSTMS CANNOT BE RULED OUT THURSDAY AFTERNOON/EVENING ACROSS THE REGION...BUT THE UNCERTAIN DEGREE OF MOISTENING/DESTABILIZATION PRECLUDES SEVERE PROBABILITIES AT THE DAY 3 JUNCTURE.

...DISCUSSION... 00Z ECMWF/GEFS/UKMET ARE IN GOOD GENERAL AGREEMENT WITH DEPICTIONS OF A RELATIVELY AMPLIFIED/SOMEWHAT STAGNANT LARGE SCALE PATTERN THIS WEEKEND INTO EARLY NEXT WEEK. THE SHORTWAVE TROUGH AS DISCUSSED IN THE DAY 3 OUTLOOK IS EXPECTED TO GENERALLY WEAKEN/MINOR OVER THE MIDWEST BY DAY 4/FRIDAY...WITH CYCLONIC/NEBULOUS UPPER FLOW OTHERWISE PREVALENT FROM THE ROCKIES TO THE SOUTH-CENTRAL PLAINS LATE THIS WEEK. NO 30 PERCENT SEVERE AREAS ARE WARRANTED AS NO PARTICULARLY WIDESPREAD/CONSEQUENTIAL SEVERE RISKS ARE CURRENTLY ANTICIPATED.

NONETHELESS...AT LEAST ISOLATED/POSSIBLE SEVERE RISKS WILL EXIST INTO THE WEEKEND. FOR DAY 4/FRIDAY...SOME SEVERE TSTMS MAY BE POSSIBLE ACROSS PORTIONS OF THE LOWER MO VALLEY/MIDDLE MS VALLEY NEAR A SURFACE FRONT/REMNANT FRONTAL ZONE...WITH POSSIBLE SEVERE DEVELOPMENT LESS CERTAIN IN THE PRESENCE OF GREATER CAPPING/NEBULOUS FORCING FOR ASCENT WITH SOUTH-SOUTHWESTWARD EXTENT ACROSS OK/NORTH TX IN VICINITY OF A DRYLINE/WEAK FRONT. OTHER STRONG/POSSIBLY SEVERE TSTMS MIGHT BE POSSIBLE ON DAY 4/FRIDAY ACROSS THE CENTRAL HIGH PLAINS IN THE PRESENCE OF LOW-LEVEL UPSLOPE FLOW/MODERATE VERTICAL SHEAR. BY DAY 5/SATURDAY...SOME SEVERE TSTMS MAY BE POSSIBLE ALONG THE SOUTHEASTWARD ADVANCING FRONT ACROSS PORTIONS OF OK/NORTH TX TO THE ADJACENT ARKLATEX AND MID-SOUTH REGIONS.

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CNTRL/SRN HIGH PLAINS...

...CNTRL/SRN HIGH PLAINS...

WELL DEFINED UPPER LOW OFF THE SRN CA/NRN BAJA COAST...CENTERED NEAR 29N/127W...WILL EJECT INLAND EARLY IN THE DAY2 PERIOD BEFORE LIFTING NEWD INTO CO/NM BY 27/00Z. THIS FEATURE WILL THEN SHIFT INTO THE HIGH PLAINS DURING THE OVERNIGHT PERIOD. AS THE TROUGH SHIFTS ACROSS THE ROCKIES LOW LEVEL FLOW WILL UNDOUBTEDLY RESPOND AND BECOME DECIDEDLY SELY ACROSS THE HIGH PLAINS. WHILE THE LATEST SHORT RANGE MODELS HAVE STRUGGLED RECENTLY REGARDING THE AGGRESSIVE BOUNDARY LAYER MOISTURE RETURN...IT APPEARS A LEGITIMATE MOISTURE SURGE WILL SPREAD ACROSS THE SRN PLAINS WARM SECTOR OVER THE NEXT 24-48HR AND 60-65 SFC DEW POINTS MAY BE IN PLACE ACROSS THE ERN TX/OK PANHANDLE REGION BY PEAK HEATING. TIMING OF THE UPPER TROUGH WILL FAVOR OVERNIGHT CONVECTION THOUGH STRONG BOUNDARY LAYER HEATING SHOULD CONTRIBUTE TO DESTABILIZATION WITHIN THE UPSLOPE REGION FROM THE TX PANHANDLE INTO EXTREME SERN CO. FOR THIS REASON IT APPEARS SCATTERED THUNDERSTORMS WILL BEGIN DEVELOPING AROUND 21-22Z. FORECAST SOUNDINGS SUGGEST SBCAPE COULD EASILY EXCEED 2000 J/KG WITHIN A SHEARED ENVIRONMENT THAT WILL STRONGLY SUPPORT SUPERCELLS. FAVORABLY SHEARED AND BACKED LOW LEVEL FLOW ALSO LENDS CREDENCE TO THE POSSIBILITY OF TORNADOES. HAVE INCREASED THE SEVERE PROBS ACROSS THE HIGH PLAINS TO ACCOUNT FOR THE LIKELIHOOD OF POTENTIALLY TORNADIC SUPERCELLS IN ADDITION TO VERY LARGE HAIL. LATE AFTERNOON/EVENING SUPERCELLS WILL ALSO DEVELOP FARTHER NORTH ACROSS ERN CO WITHIN STRONGER ZONE OF FORCED ASCENT. THIS ACTIVITY COULD EASILY SPREAD INTO SWRN NEB/NWRN KS BY MIDNIGHT AS LLJ INCREASES DURING THE OVERNIGHT PERIOD.

...TN VALLEY TO MIDDLE ATLANTIC...

DIGGING UPPER TROUGH OVER THE OH VALLEY/NEW ENGLAND STATES WILL ENSURE SFC PRESSURES RISE WEST OF THE APPALACHIANS DURING THE DAY2 PERIOD. THIS IN TURN WILL FORCE A COLD FRONT ACROSS WV/KY INTO TN DURING THE LATE AFTERNOON HOURS. EARLY IN THE PERIOD IT APPEARS STRONG LOW LEVEL WARM ADVECTION WILL BE PARTLY RESPONSIBLE FOR THUNDERSTORM CLUSTERS THAT WILL SPREAD ACROSS PORTIONS OF THE MIDDLE ATLANTIC REGION AHEAD OF SFC LOW. THIS EARLY ACTIVITY IS NOT EXPECTED TO BE PARTICULARLY SEVERE AS INSTABILITY WILL BE SOMEWHAT LACKING. HOWEVER...THERE IS SOME CONCERN THAT STRONG BOUNDARY LAYER HEATING WILL CONTRIBUTE TO SIGNIFICANT INSTABILITY ALONG THE ADVANCING COLD FRONT. WITH WEAK HEIGHT RISES EXPECTED ALONG THE TRAILING BOUNDARY IT/S NOT ENTIRELY CLEAR HOW MUCH CONVECTION WILL EVOLVE IN THE WAKE OF THE AFOREMENTIONED UPPER TROUGH. ADEQUATE SHEAR WILL BE IN PLACE FOR POTENTIAL STORM ORGANIZATION AND A SLIGHT RISK MAY BE REQUIRED IN LATER OUTLOOKS TO ACCOUNT FOR ISOLATED SUPERCELLS. AT THIS TIME WILL MAINTAIN 5% SEVERE PROBS ALONG THE ADVANCING BOUNDARY...BUT IF IT BECOMES MORE CLEAR THAT STORMS WILL FORM IN GREATER CONCENTRATION THEN THESE PROBS WILL BE INCREASED TO ACCOUNT FOR DAMAGING WINDS/HAIL.

...SYNOPSIS... MODELS INDICATE THAT THE LARGE-SCALE MID/UPPER FLOW PATTERN WILL REMAIN BLOCKY THROUGH THIS FORECAST PERIOD...WITH A NUMBER OF EMBEDDED SMALLER SCALE DEVELOPMENTS REMAINING UNCERTAIN. THIS INCLUDES THE SUBSEQUENT EVOLUTION OF A HIGH CENTER...WHICH IS EXPECTED TO DEVELOP OVER THE CENTRAL CANADIAN PROVINCES BY 12Z FRIDAY...THE SOUTHERN PORTION OF A SPLITTING UPPER IMPULSE MIGRATING INLAND ACROSS THE PACIFIC NORTHWEST AND NORTHERN INTERMOUNTAIN REGION...AND ANOTHER LOW EMERGING FROM THE LOWER LATITUDE PACIFIC. AFTER INITIALLY MAINTAINING ITS CYCLONIC CIRCULATION...MODELS ARE SUGGESTIVE THAT THE SOUTHERN FEATURE MAY ELONGATE OVER THE MID MISSOURI VALLEY FRIDAY...TO THE SOUTH OF THE HIGH...WHILE THE HIGHER LATITUDE IMPULSE REDEVELOPS INTO THE MORE PROMINENT LOW ACROSS THE NORTHERN ROCKIES.

SOUTH/EAST OF THE HIGH CENTER...AND WEST OF A BROADENING UPPER CLOSED LOW OVER SOUTHEAST CANADA AND THE NORTHEASTERN U.S...COLD SURFACE RIDGING MAY NOSE AS FAR SOUTH AS THE MIDDLE MISSISSIPPI AND LOWER OHIO VALLEYS. AT THE SAME TIME...CONTINUED GRADUAL MOISTENING OF THE BOUNDARY LAYER OVER THE GULF OF MEXICO MAY OCCUR...BUT A SUBSTANTIVE INLAND RETURN FLOW STILL APPEARS UNLIKELY.

...CENTRAL PLAINS INTO MIDDLE MISSISSIPPI VALLEY... GIVEN UNCERTAINTIES ASSOCIATED WITH BOTH THE EVOLVING UPPER PATTERN AND THE MAGNITUDE OF THE AVAILABLE LOW-LEVEL MOISTURE... CONTINUATION OF SEVERE POTENTIAL DEVELOPING ON THURSDAY ACROSS THE CENTRAL HIGH PLAINS REMAINS UNCLEAR...AS A SURFACE WAVE DEVELOPS EASTWARD ALONG A FRONT INTO THE LOWER PLAINS AND MIDDLE MISSISSIPPI VALLEY. AT LEAST SOME SIGNAL EXISTS IN THE GUIDANCE FOR A LATE AFTERNOON ISOLATED SUPERCELL THREAT...AND SUBSEQUENT UPSCALE GROWTH OF A MESOSCALE CONVECTIVE SYSTEM DURING THE EVENING...SO LOW SEVERE PROBABILITIES APPEAR WARRANTED. BUT...THERE IS NOT ENOUGH CONFIDENCE FOR SLIGHT RISK PROBABILITIES AT THE PRESENT TIME.

...DISCUSSION... SHORT WAVE DEVELOPMENTS THROUGH THE EXTENDED FORECAST PERIOD REMAIN HIGHLY UNCERTAIN. HOWEVER...MEDIUM RANGE MODELS ARE SUGGESTIVE THAT THE BLOCKY UPPER FLOW PATTERN MAY TRANSITION TO A MORE PROGRESSIVE ONE...AT LEAST ACROSS THE NORTHERN TIER STATES... WHERE A MORE DISTINCT AND STRONGER ZONAL BELT OF WESTERLIES MAY EVOLVE DURING THE EARLY TO MIDDLE PORTION OF NEXT WEEK. HIGHER MOISTURE CONTENT AIR ALSO APPEARS LIKELY TO RETURN INLAND OFF A RECOVERING GULF OF MEXICO BOUNDARY LAYER THROUGH MOST AREAS EAST OF THE ROCKIES...INCLUDING 65-70F SURFACE DEW POINTS AS FAR NORTH AS THE EAST CENTRAL PLAINS/LOWER MISSOURI VALLEY REGION BY NEXT TUESDAY/WEDNESDAY. INCREASING INSTABILITY WILL YIELD INCREASING CONVECTIVE POTENTIAL...PROBABLY INCLUDING DAILY SEVERE WEATHER THREATS. HOWEVER...ANY SIGNAL FOR A REGIONAL TYPE SEVERE WEATHER EVENT REMAINS LOW...AND GENERALLY CONFINED TO THE LATTER PORTIONS OF THE PERIOD...WHEN PATTERN PREDICTABILITY IS AT ITS LOWEST.

My sister called 911 to report it, and as she was on the phone ("calm down, ma'am") the town's tornado siren went off.

Again, nobody hurt at the ballfield, but I don't know about elsewhere.

My sister said she saw the clouds above circling, as she was looking for her car keys in a downpour of rain, and then suddenly trash cans were being thrown, desbris flying, and then cars in the parking lot flipping over.

Just heard from my sister. Tells me she was interviewed by the Nashville newspaper (The Tennessean). She is amazed nobody was hurt. Several cars flipped in the parking lot where lots of kids were all heading to their cars. Scoreboard knocked over, too.

Just heard from my sister. Tells me she was interviewed by the Nashville newspaper (The Tennessean). She is amazed nobody was hurt. Several cars flipped in the parking lot where lots of kids were all heading to their cars. Scoreboard knocked over, too.